If you’ve been dreaming of a blue Christmas, take heart. James Cameron is about to drop a sack full of cobalt down the chimney with “Avatar,” his azure-hued sci-fi extravaganza that’s sure to yield piles of green.

Or, at least it better make a bunch, given its Nordstrom-like price tag of $300 million. That’s a lot of coin to drop on such a risky gift, especially one given without any big-name stars included.

That means no Arnold, no Leo and no Kate; just some Australian guy named Sam, who’s as pretty as a bow but as empty as a box.

The last name is Worthington, if anybody cares, and he is easily the dullest lead Cameron has ever cast. But then humans aren’t what “Avatar” is all about. It’s special effects. And for the most part, they’re impressive, as Cameron summons plenty of bang for his bucks in creating a computer-generated 3D world that feels and looks alive – even if his characters do not.

But pretty pictures and giant fireballs will only get you so far, particularly with a running time of nearly three hours. With that kind of investment you better give people something to keep their tired butts in the seats. And on that front, or should I say backside, “Avatar” falls short.

That’s because the story, a laughably simplistic tale of imperialism and mechanized warfare in the 22nd century, is little more than a “Dances With Wolves” redo with bits and pieces of “The New World” and “Jurassic Park” tossed in.

Set in 2154, Cameron’s colossus picks up 30 years after an American invasion of a distant utopia called Pandora, located in a galaxy far, far away, where we’re not welcome and our motives are nefarious at best.

If this is sounding like a metaphor for the U.S. involvement in Iraq and Afghanistan, you’re right on Cameron’s wavelength. But it’s a little disingenuous of him to criticize our government’s oil-at-any-cost mentality when he’s consuming a gazillion kilowatts of electricity just to run the banks of computers required to create “Avatar.” Ironically, the only place he conserves energy is where he needed the most juice. And that would be the inter-species romance between Worthington’s paraplegic ex-Marine, Jake Sully, and Zoe Saldana’s blue-hued amazon local, Neytiri.

Well, it’s not Jake technically, but rather his avatar, a genetically engineered hybrid manufactured by blending human DNA with that of the native Na’vi.

From a sealed cocoon in the mother ship, Jake is able to control the thoughts, speech and movements of his 10-foot-tall alter ego, which, unlike him, is able to survive in the thin Pandoran air.

His avatar is also able to walk, which makes for one of the film’s best scenes when Jake takes the big blue guy for a spin shortly after arriving on Pandora, a lush, tropical moon in the Alpha Centauri galaxy.

Page 2 of 3 - The visceral thrill of seeing him being able to walk again is potent, as he lopes through picturesque landscapes that we soon learn are about to be plowed under as part of the Resources Development Administration’s scheme to mine a highly potent energy source called unobtainium.

That’s where Jake comes in. His avatar is part of a program aimed at convincing the Na’vi that it’s better for them to peacefully abandon their sacred land than have it taken by force. The problem is that Jake – in the tradition of John Smith and Pocahontas – falls for the beautiful Neytiri the second she rescues him from a pack of blood-thirsty viperwolves.

Predictably, Neytiri, who just happens to speak English (with a Caribbean accent, no less), initially resists Jake’s advances, dismissing him as a “skowng,” which is Na’vi for “moron.” And she’s right. As played by Worthington, Jake is a moron. And his boss, Grace (Sigourney Weaver riffing on her “Alien” Ripley), isn’t about to disagree. Of course, once the lug learns to single-handedly defeat his heavily armed U.S. comrades, the bodacious gals begin to change their tune. But it’s questionable whether you will.

I know I didn’t. I was bored silly by Cameron’s ham-handed tale in which glitz trumps substance at every turn. I didn’t care about their characters, their plight or how hard it is being blue. I just wanted it to end, and that was about 45 minutes in.

And it wasn’t just the lame characters and acting. It was, of all things, the special effects. To my jaded eyes, many of them looked fake, almost cartoonish, particularly whenever flying objects were involved, be they massive prehistoric birds or Marine helicopters and spaceships.

There were also serious lapses in logic. Why, for instance, would Jake ever feel like he’s in danger? Sure, his avatar is at risk of being destroyed, but he’s not. Then there’s the matter of Pandora’s precious ore. Would it really be worth a 12-year roundtrip at exorbitant costs just to further fuel Earth’s addiction to energy? I guess we’re not supposed to think about that as much as we’re supposed to lose ourselves in the tribulations of the star-crossed lovers and their “Titanic”-sized heartbreak.

Still, you can’t help but admire the amount of work and imagination that went into “Avatar.” Especially the advancements it has forged in capture-motion technology. But from a purely entertainment angle, Cameron’s $300 million baby is nothing but a 5- and 10-cent snore.